Electrical – How to wire the old 3/4hp 115-120v 50-60Hz HVAC motor to make an exhaust fan

I had a capacitor replaced once. Everything seemed to work fine, until 5 minutes after the a/c guy left, then the fan overheated and stopped. I couldn't get him to come back, so I investigated and found that he hooked up the wires to the capacitor backwards; the fan was connected to the "run" prong on the capacitor and the motor to the "fan" prong. I switched it back and it's been running fine ever since.

Is this a belt drive or direct drive motor? If you look on the motor there should be a wiring schematic/diagram. If it is a direct drive, the colors determine the shaft speed or the RPM. Usually, Black is high, Blue is medium high, Yellow is medium low, Red is low. Or Red and Yellow could be interchanged. White is the neutral. look on the motor or wiring cover plate. The unused wire is taped off Yours is probably; black to black, blue to blue, furnace yellow to red or yellow, and white to white. Tape off the last wire. However check the wiring schematic just to be sure. If it a belt drive you will need a wiring schematic. Is the motor a single speed or multi speed? If you are not sure how to hook up the motor seek professional help.